The Offshore Voyaging Reference Site

Internal Volume—Too Much In The Wrong Place?

It’s all very well to have so much internal volume, but if all of it is taken up with berths and shower units, then where does all the ‘stuff’ go? On the charter boat we hired, for example, the forward double had a water tank beneath it, a few shelves with nothing to secure gear above the bunk on one side, and one good sized hanging locker. Nothing like enough space for two people to liveaboard for two weeks in such a northern latitude, let alone full time. You inevitably end up with people living out of their sailing bags, a situation I cordially dislike.

And how ‘stuff’ accumulates. The area under our huge double bunk forward on Pèlerin is now just about completely filled with spares, camping gear, an inflatable kayak, dive gear and all of the ‘essential’ paraphernalia of life aboard. Fortunately we have lots of locker space built in for all of our clothes for all latitudes (for us to return to work), otherwise we’d have to move out!

Too Many Cabins?

Many boats have too many cabins, in my view. It’s all very well to have four cabins, but will you sail with eight people aboard regularly? Really? If yes, then well and good, but if not, then why not convert at least one cabin to stowage, using boxes instead. On a new build this is far more simple, but even with an existing boat it can be straightforward enough, and if carried out with forethought it should be possible to change it back to a sleeping cabin before re-sale. If you do this, it’s important to start by planning how you’ll go about breaking up the space to store all of those essential items that you can’t leave behind.

Many hardware stores sell ‘storage’ boxes, and these look tempting, but in my experience are nowhere near robust enough and never last long in a boat. A good alternative I’ve found are fish boxes, which are not only incredibly tough, but allow ventilation, and can have straps attached to them to keep them in place. Great for wet gear in external lockers, fine for stores in the dry. They can be stacked, and strong nylon netting (we use it everywhere) used to secure their contents. In deep external lockers where you can get in and stand, a good way to avoid slipping and keep gear off the internal structure is to fit fibreglass decking (as seen in many marinas) which can be cut with a jigsaw to fit even the most awkward spaces. Light, cheap, rotproof and virtually unbreakable, it is also useful to keep gear out of the inevitable small quantities of water that can gather in cockpit lockers, or to make draining shelving in the anchor locker.

Not Enough Tankage?

Finding space for adequate fuel and water tanks can be another problem where so much space is given over to in-harbour life, especially as most modern boats have very shallow bilges that already limit available space. Not having adequate supplies of either is not just a nuisance, but can compromise safety and autonomy, so it makes sense to find ways to make those deficiencies good.

For me, having enough water to have (at least) an occasional shower is the ultimate luxury, a legacy of so many years aboard charter boats full of guests, who naturally had first call on the limited quantities we could carry. So we installed a watermaker to make that possible, our one concession to complexity, but obviously involving more expense and maintenance so it’s not for everyone. For many people, a simple awning or rain catching device will suffice, and is a sensible thing to carry in any case, and obviously with spare cans for general or emergency use.

Install Extra Tanks

But I’ve yet to find a boat that didn’t have space somewhere where an additional tank or two couldn’t be installed for either fuel or water. Installing extra tanks can make a big contribution to overall range, and can take up less space than jerrycans. On my last boat we had flexi water tanks that gave absolutely no problem for over 17 years, with no more maintenance than installed tanks. The only critical factor with these tanks is that any space for them must be free of any sharp edges where they can be abraded. They do move around, especially when less than full, and finding really effective ways to strap them down can be a challenge. Moulded HDPE tanks are now a good option for fuel and water, especially as many of the makers like Tek-Tanks can build custom designs to fit awkward spaces, with internal baffles (a big advantage) almost always fitted. These can be a good option for updating an existing boat that has no holding tank, too.

Building a boat to your own liveabord specification is rewarding, but costly. For many people, converting an existing boat will be a far more realistic option. But time spent in getting this right will pay dividends down the line, making better use of the available space and leaving you with a far more practical, comfortable home.

More Articles From Colin on Good Design:

  1. Modern Yacht Design—What Do We Need?
  2. Parallel Or Swept-Back Spreaders?
  3. Volume—And Its Effects
  4. Internal Volume—Ready For Sea?
  5. Internal Volume—Too Much In The Wrong Place?
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Victor Raymond

Colin, Great article! Every point well taken. I was wondering about flexible tanks. I have had them on airplanes but have yet to hear how they fare on boats. I have 1000 liter capacity for both water and fuel and am hoping that is enough. The expedition yacht Seal does not have a water maker and they claim to do quite well with water falls and creeks. For my boat we have a flexible tank fitted for the hard dinghy with a 12v pump to move the liquid up and into the main tanks. One quick question: you speak of fish boxes, could that be what we refer to a milk crates? Thanks again for the great post.

Colin Speedie

Hi Victor

Good quality flexible tanks are double skinned, and can fit into awkward spaces very well – maximum benefit can be gained if they are custom made to fit the space. I’ve never had one leak, but the fittings where they meet the inlet/outlet hoses sometimes leave a bit to be desired. The principal weakness they have (and where solid tanks have a real advantage) is that they are not baffled, and that’s a real drawback, especially on bigger tanks.

Working with a boat in remote places usually means carrying several 25L cans, and filling up with them wherever and whenever you can, and I have to say I became heartily sick of it! Great idea re the flexible tank and the hard dinghy, with the electric pump for transfer, which would certainly work well when off the beaten track, and save your back too.

Yes, of course you’re right, although milk crates (over in the UK at least) are smaller. Sometimes my English vs US terminology fails me – sorry. Fish boxes (crates?) have no dividing pieces inside, and stack really well – as they’re designed to do, and are light and tough. They are a cheap and flexible way to keep gear stored anywhere in the boat.

Thanks for the kind words

Best wishes



Its far too late in the history of “progress” to reopen the old debate about full keel vs fin keel boats. But everything is a trade off. The Cape George 36* that I built and lived aboard for a decade back in the day carried 200 gallons of water and 65 of fuel under the cabin sole along with 10,500# of lead. No need to try to sleep on top of a sloshing water tank or clutter the decks with jerry cans! All that ballast enabled her to carry 100 sq. ft more sail than a Valiant 40 of the same era, and she just seemed to get faster the more weight you put in her. Guess which boat was fastest in 15 knots of breeze? Put the helm down and you were hove to behind a slick the size of a small freighter. Of course docking maneuvers needed to be planned 100 yards in advance—one of the reasons we no longer see this style of boat.

* A design developed from the Tally Ho Major that Atkins drew in 1942 for $100.

John Harries

A really good point about hull shape and tankage. Our “Morgan’s Cloud” despite having a fin keel carries 290 gallons of fuel and 250 of water under the sole. The secret is her symmetrical deep V section. Although we do try and keep her light, as you say, weight just does not hurt her performance, at least as long as it is not in the ends.

Colin Speedie

Hi RDE and John

Good that you both raise the important point of load-carrying capacity, which is another weak spot with lighter displacement boats. And deep bilges enable tanks (and so weight) down where it needs to be.

And if you don’t spend all of your time going in and out of marinas, then long keelers still have a lot going for them.

Best wishes


John Harries

Hi Colin,

Another great post in a great series. I agree with all of your points, but the one that really jumps out at me is “too many cabins”.

One of the many things that make “Morgan’s Cloud” a really great voyaging live-aboard boat, at least for us, is that she only has three cabins, two sleeping (one fore one aft) and the salon, rather than the four, or even five that many modern 50-foot boats have.

This leaves plenty of room for a big forepeak, massive lazaret, huge engine room and a work shop with bench. Also tons of storage. All of this despite the fact that her narrow sea-kindly hull has less volume than many modern 45-boats.

Colin Speedie

Hi John

As you know, we opted for the same layout with our boat, and it suits our needs very well. Opting for one less heads, and one less cabin has freed up a huge amount of valuable space.

But as the old saying goes, ‘if you’ve got some room, you’ll soon fill it’, and even with the available space we have, we still have to be ruthless about what stays on the boat!

The only thing we don’t have is a huge engine room – but you can’t have everything, can you.

Glad you’ve liked the series.

Best wishes



Completely agree with the points made, notably on cabins. The worst thing is that the extra cabins end up filled up with junk anyway, to the point they just can’t be used for guests whatsoever !

A point you didn’t make in the series is the importance of having an adequate storage for sail and ropes. On many boats, the spinnaker is stored below a bed and needs to go through all the companionway and the gangways, which is unpractical and even dangerous to some extent.

Thank you for an interesting read !

John Harries

Hi Brann,

That’s a very good point. And the worst part is having to drag a wet spinnaker back through the accommodation and then live with it!


Hi Colin,
Too many cabins? The only thing worse is having too large a cabin. Especially if it is 16′ wide and has no handholds. Even though it was 8 years ago I was forcefullly reminded about how much fun it is to be thrown all the way across one of the deck salon skating rinks that the marina sailing market loves. Went to the doctor last week to have the elbow that was injured X-rayed again. The bone spur looks like a giant fish hook, and will serve to extract $10,000 from my pocket book and a couple of months of post surgical recovery.

John Harries

Hi Richard,

I agree, and I’m sure Colin does too. The super yacht I was guide on a Greenland trip on had a salon that had to be 25′ across with polished varnished floors, scared the hell out of me every time I had to cross it at sea. She also had another “feature”: From the wheelhouse entrance to the helm and winch island was about 20′ across a raised deck (well above the side deck rails) with absolutely nothing to hold onto.

Scott Johnson

I am renovating at Cape George 36 for sailing the US east coast, eastern Canada, the Caribs and Europe, especially northern Europe. Currently, the boat has a Raritan Elector Scan effluent treatment system, but no holding tank. Whether effluent is treated or not, all is simply discharged overboard. New England is a no discharge zone, which makes this arrangement illegal inside the 3 mile limit, as I understand the regs. I’m resigned to installing a holding tank, and located a spot in the forward bilge that appears to be suitable. Should I keep the Elector Scan? At this juncture I’m planning on removing the Elector Scan to simplify systems. However, sewage requirements in other parts of the world may militate against that. Would love to hear feedback from others, particularly in regard to the areas I mentioned. Not really the fun part of a boat, but ya do what needs to be done! Thanks in advance. Didn’t see another subject heading where this topic seemed to fit.

John Harries

Hi Scott,

Sorry, I really don’t have a good answer for this. In fact I’m not sure there even is a good answer! All I can tell you is that we have a 25 gallon holding tank, and that’s a bit small, 35 would be better. Here are another couple of short articles that may help: (The more PVC pipe you can use, the less it will stink.) (Simply the best valves we have found, and we have tried a bunch).

I’m also a huge fan of Lavac heads, simple and reliable. (In 25 years I have never had one block up.)

The Raritan is a great system. Going over to zero discharge and by so doing effectively making systems like the Raritan obsolete must be one of the stupidest decisions law makers have ever made. The result is that now most people cheat and pump it out raw, whereas, if we had encouraged treatment options like the Raritan, we would probably have some really good ones by now.


Hi Scott
On the Cape George 36 that I built and lived on for 7 years I had a Wilcox Skipper which functioned flawlessly. I pumped directly overboard without a minute of guilt, even while in a marina in Puget Sound. My reasoning is as follows: The marina in question had storm drains flowing directly outside of the breakwater that drained the oil leakage from a 400 car parking lot and an extensive urban area adjacent to it. Plus it housed 1,000+ boats with toxic bottom paint bleeding into the water. It also benefited by daily flushing of a 10-15′ tidal range. Any effluent I contributed to the water only contributed to the health of the marine environment and supported the crabs and barnacles that managed to live there. I wouldn’t pump directly overboard today for fear of being carted off to jail to serve a 20 year sentence. Nor would I do so in bays with less aggressive tidal flushing or crowded anchorages that predominate in the Caribbean and many cruising grounds of the present day.

The second owner of my Cape George was a Microsoft exec. Being a techie, he filled the entire area under the forward berth with an electric head and treatment system. If I had any brand of electric head on anything other than a large motor yacht I’d throw it overboard ASAP .

The third owner yanked all that crap out (the treatment system) and replaced it with a composting Airhead. I did live on board with a composting head for two weeks in the Bahamas. I can testify that it was odorless as was the bag of compost we removed at the end of the cruise. Managing the toilet paper was less pleasant— .

Scott, if you want to chat about your Cape George refit drop me a line. John has my contact information.